United States
 Environmental Protection
 Agency
Chesapeake Bay
Program
Annapolis MD 21403
Research and Development
EPA-600/S3-82-089 Jan. 1983
Project Summary
 Fate, Transport, and
Transformation of Toxics:
 Significance of  Suspended
 Sediment  and  Fluid Mud

 Maynard Nichols, Richard Harris, Galen Thompson, and Bruce Nelson
  This research sought to determine
the distribution of selected metals in
suspended material and fluid mud, to
identify  potential  zones  of  toxic
accumulation,  and  to  trace  their
transport routes.
  Between  March  1979 and  April
1980, observations of flow, salinity,
suspended material, pH, and dissolved
oxygen were made in Bay-wide longi-
tudinal sections, and at four anchor
stations in  the  Northern  Bay.  The
observations covered  a range  of
conditions,  including seasonal high
and low river discharges,  sediment
influx, neap-spring tide range,  and
oxygenated-anoxic water. Samples of
suspended material, fluid mud, and
bed  sediment  were analyzed for
particle size,  organic  matter,  and
metal content.
  Metal concentrations of As, Cu, Mn,
Ni, Pb. Sn, and Zn in fluid mud and bed
sediment,  per  gram  of  material,
decrease seaward from a maximum in
the   Baltimore-Susquehanna  River
area.  The concentrations of metals
Mn, Pb, and Zn are four to six times
greater than Fe-corrected average
shale, indicating major human input,
and significant accumulation in this
zone.
  Metal concentrations of Cd, Cu, Pb,
Ni,   and  Zn  are maximal in
surfacesuspended material from the
central  Bay. They are higher than
landward near-potential sources, and
they  exceed concentrations in bed
sediment  two to 80 times.  The
enrichment is not natural compared to
average shale or plankton; it is most
likely created by bio-accumulation.
  Transport of particle-associated
metals from major sources follows
either  hydrodynamic pathways
leading  to particle accumulation by
the  estuarine  circulation or
bioecological  routes leading to
bio-accumulation.
  Management  and  monitoring
strategies  are  provided to reduce
potentially toxic metals to acceptable
levels  and  warn management
agencies of toxic hazards.
  This report  is submitted in fulfill-
ment of Grant R806002-01 -1 by the
Virginia Institute of Marine Science,
School of Marine Science, College of
William and Mary, under sponsorship
of the U.S. Environmental Protection
Agency. This report covers the period
July 1, 1978 - August 30, 1982.

  This Project Summary was develop-
ed by EPA's Chesapeake Bay Program.
Annapolis, MD. to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).

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Introduction
  Each year, a substantial load of trace
metals enters Chesapeake Bay, from
both  natural  and  human  sources.
Regional production of toxic  metals is
increasing  with  increasing  industrial
activity and sewage discharge. At least
half of  all cadmium  (Cd), lead (Pb),
copper   (Cu),  and  chromium (Cr)
reaching the Bay results from sewage
and industrial  waste. Although low
concentrations of metals are  important
to  environmental quality  of the Bay,
there is cause for concern if concentra-
tions are excessive. Toxic effects have
not been demonstrated, but disturbing
changes  in the Bay environment have
been observed: a decrease in oyster and
striped bass populations, a  lack of shad
runs  in  the upper bay, and  declining
clam catches. Knowledge of contamina-
tion  levels,  transport  routes,  and
reservoirs of potential  contaminants is
necessary because toxicants  may alter
the quality of the Bay over periods of
time.
  This study investigates  the  role of
suspended sediment and fluid  mud in
the  fate   of  toxic   metals  in  the
Chesapeake Bay system. Fluid mud, an
intermediate  stage between  mobile
suspended  material  and  mud,  is
chemically important  because  it is  a
reservoir for potentially toxic metals and
a medium for chemical transfer.
Procedure/Methodology

  A series of field observations defined
the  Bay-wide  distribution  of  metal
contaminants  in  the following  way:
suspended material was  collected for
analysis of toxic metals; water in which
the metals occur was characterized; and
sediments with which metals associate
were analyzed  for particle  size and
physical properties. Temporal variations
of sediment and metal loading were
established, and  potential  zones  of
metal accumulation and their transport
routes  were  identified. Field
observations  included  contrasting
conditions such  as seasonal high-low
river discharges and sediment influx,
neap-spring tide range, and oxygenated-
anoxic water differences. A  survey of
122 stations, identifying these variables,
and recording the parameters of tem-
perature, salinity, dissolved oxygen, pH,
and total amounts of suspended mate-
rial,  resulted in  5576 measurements,
including analyses of six to 11 metals.
   Bed sediment and  fluid  mud were
 obtained  with  a  stainless   steel
 Smith-Maclntyre*  grab or Bouma box
 core. Suspended materials collected on
 Nuclepore  filters  were  analyzed  by
 flame atomic absorption  for iron (Fe),
 manganese  (Mn),  and zinc  (Zn).
 Flameless atomic absorption was used
 to obtain concentrations of arsenic (As),
 cadmium (Cd), copper (Cu),  mercury
 (Hg),  nickel (Ni), lead (Pb), and tin (Sn).


 Results and Conclusions

   The maximum turbidity zone (stations
 12 to 18) contains high suspended
 loads, fine particle size, and low organic
 carbon  percentages.  Low suspended
 loads, coarse  particle size,  and high
 organic percentages are common to the
 central Bay zone (stations eight to 11);
 stations one to seven, representing the
 near-entrance  reaches,  have
 intermediate  suspended loads,
 moderate particle  size, and  moderate
 organic percentages. Conditions in the
 deeper  portions of the  central  Bay
 region favor accumulation of metals and
 fluid  mud  because  of  fine-grained,
 moderately organic sediments  which
 deposit rapidly.
   Metal  distributions  in suspended
 material  are vertically stratified, with
 mean-surface  and  mid-depth concen-
 trations greater  than  near-bottom
 depths. Cd, Cu, and Pb of surface and
 mid-depth waters are three to 12 times
 higher in summer than in spring. Con-
 centrations of Cd, Cu, Pb, Ni, and Zn are
 maximal in surface suspended  matter
 from  the central Bay, suggesting bio-
 accumulation  of metals  from distant
 sources.
   Bay water is well-buffered against pH
 change and is oxygenated, except in
summer when near-bottom water of the
central Bay (below 10m depth) is anoxic.
Also, time, depth, and distance seaward
are conditions which  affect physical,
chemical, and sedimentologic rates of
transport and accumulation of toxics.

Recommendations

   By  dealing with  Chesapeake Bay as
 an entity, the state of the Bay can be
 improved  by  reducing input  of such
potentially toxic metals as Cd, Cu, Ni, Pb,
and Zn from wastewater and industrial
discharges. Nutrients which stimulate
organic production should be reduced to
alleviate the suspended solids load, of
which  some  40  to   60   percent  is
composed  of  organic  material.
Entrapment of river-borne sediment can
be deterred by regulating inflows during
periods of high sediment influx.
  Potentially  toxic metals  should be
managed by controlling them at their
sources,  by  learning  the long-term
changes and "far-field" effects in zones
of  accumulation,  by  recognizing
amounts of toxicants  in  the  system
which are above natural levels, as well
as the associations between metals and
sediment.  A monitoring system of the
Bay and its tributaries, with a scientific
data  base, should be  established to
warn  Bay managers  of toxic hazards.
Research should consider such factors
as  bio-accumulation   of   toxics  in
plankton, the significance of repetitive
sediment resuspensions, and the role of
tributaries as sinks or sources of metals
and sediments.
*Mention of tradenames or commercial products
does  not constitute endorsement or
recommendation for use by the U S Environmental
Protection Agency.

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Maynard Nichols, Richard Harris, Galen Thompson, and Bruce Nelson are with
  the Virginia Institute of Marine Science, Gloucester Point, VA 23062.
Duane Wilding was the EPA Project Officer (see below for present contact).
The complete report, entitled "Fate, Transport,  and Transformation of Toxics:
Significance of Suspended Sediment and Fluid Mud," (Order No. PB 83-116
  426; Cost: $13.00, subject to change) will be available only from:
       National Technical Information Service
       5285 Port Royal Road
       Springfield, VA22161
       Telephone: 703-487-4650
For information contact David Flemer at:
        Chesapeake Bay Program
        2083 West Street, Suite 5G
        Annapolis, MD21403

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                                                                    V
United States
Environmental Protection
Agency
Center for Environmental Research
Information
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                                                                              U S  GOVERNMENT PRINTING OFFICE  1983	 659-O17/C
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